With about 680,000 Twitter followers, 70,000 friends on Facebook and more than 4.2 million views of its YouTube videos, meet Spain's unlikely social media star: the National Police.

Among law enforcement agencies, it has the second most Twitter followers after the FBI, according to Carlos Fernandez Guerra, social media manager for the Madrid-based police force. It's also the world's most retweeted government institution, averaging 16,000 times a week, he said.

"While the FBI mostly publishes statements, we are more proactive and use social media in a preventive way," he said. "We find Twitter the most useful communication tool to connect with citizens and chase criminals."

Useful and inexpensive.

Although social media was initially geared toward helping people connect with each other and giving individuals a louder voice in the online world, some law enforcement agencies are finding it an effective -- and cheap -- way to fight crime.

"Twitter and social media in general have provided us with a very important platform to reach citizens massively as our budget is very low," Fernandez said.

But just having a Twitter account (@policia
) isn't enough. Although the Spanish police have been tweeting since 2009, it wasn't until the arrival of Ignacio Cosido, a more tech-savvy director general, that the agency's social media efforts took off.

Fernandez, a former financial journalist, also boosted the police's popularity by crafting provocative tweets such as "Droga = Caca" (drugs = excrement) and "Ayudanos y les trincaremos" (help us and we'll capture them).

It recently created one hashtag, #pedetecorporativo, which loosely translates into "corporate drunkenness," to remind people that they shouldn't drink during company Christmas dinners if they need to drive.

The police's social media push seems to be paying off. Shortly after promoting the agency's e-mail address, antidroga@policia.es, on social media last year, they received about 500 e-mails from citizens providing tips about drug dealers or crime in the country, Fernandez said. This "tweet raid" campaign led to about 350 arrests and the seizure of more than 450 kilos of drugs including cocaine and pot.

Because of this success, other police departments from around the world, especially in Latin America, are approaching their Spanish counterparts to learn how they can use social media to catch criminals.

"They’ve been very smart in understanding how community management works, and have been effective in communicating and responding to citizens in a colloquial and close way," said Enrique Dans, a professor of information systems at IE Business School in Madrid. "That way people feel more comfortable to get in touch with the police."

Speaking of TV, one of the Spanish police's most popular tweets was timed to the airing of the last episode of "Breaking Bad" in Spain: "If you play Breaking Bad, you'll end in a scene from Prison Break."